Russia's massive quake has already triggered at least 10 aftershocks, and could continue for months, according to scientists.

Millions of people were evacuated, as minds cast back to the devastating tsunami of Boxing Day 2004 in the Indian Ocean and Japan 2011, both triggered by similarly large earthquakes. But today's tsunami has been much less severe, even though it's brought some damage.

The 8.8 magnitude quake off Russia that triggered tsunami warnings across the Pacific occurred on what is known as a "megathrust fault", where the denser Pacific Plate is sliding underneath the lighter North American Plate.